Two cases with partial trisomy 9p: molecular cytogenetic characterization and clinical follow-up.

This paper describes two patients with partial trisomy 9p and partial trisomy 14q due to 3:1 segregation from de novo maternal reciprocal translocations. The breakpoints are different from previously described 9;14 translocations and their 3:1 segregation products. The clinical phenotype of both cases is compatible with the partial trisomy 9p syndrome. We present the follow-up of both patients from birth up to age 7 years. Partial trisomy 9p is a frequently described chromosome abnormality. This does not appear to be related to a breakage sensitive locus on chromosome 9p, since the trisomic fragments of the published cases are heterogeneous. In the two cases described here, GTG-banded karyotyping suggested that the 9p breakpoints were similar; DNA marker analysis, however, showed them to be different. Such DNA studies will be necessary to define the genotype-phenotype relation in partial trisomy 9p syndrome.